The largest dwarf planet in the Asteroid Belt, Ceres, is going to be charted soon by NASA’s Dawn, as the spacecraft has started its final approach to the asteroid. NASA’s solar-charged probe is scheduled to touch base in March, when Ceres will catch the spacecraft in orbit. With the assistance of its electrically-controlled particle propulsion engine, the space shuttle will achieve an 8,400 miles circular orbit from Ceres by the end of April.
Dawn’s aim is to inspect Ceres from various heights, gathering data about its chemical composition, internal framework and surface properties.
Researchers assume that the asteroid was shaped like the rest of the planets in our galaxy, but it did not manage to gather enough material to develop size. Ceres has a round shape and it measures only 600 miles across, as indicated by pictures captured by the Hubble Space Telescope.
Dawn was launched seven years ago and its mission is to pay visits to the largest asteroids in our Solar system. After being sent in space in September 2007, the spacecraft circled the asteroid called Vesta between July 2011 and September 2012. Since then it started a new voyage to Ceres. Once the probe succeeds orbiting Ceres it will become the first space apparatus to circle two space rocks.
Dawn has managed to survive so long in space thanks to three ion motors, which use both electrical power and xenon gas to produce a gentle push. Traditional thrusters powered by chemical fuels generate stronger power, but ion ones are considered more effective. By using its less potent particle engines for months at a time, Dawn is setting its route through the earth’s planetary group in a manner that chemically-fueled missions could not.
The spacecraft encountered some problems in September, when the propelling system was disturbed by strong cosmic radiation. The particle emission stopped Dawn’s ion pushing system for about four days. But expert cosmic navigators at NASA’s Jet Propulsion Laboratory came up with a new route for the probe, so it would still be able to reach Ceres at about the same time as set before the cosmic radiation event.
The spacecraft will be captured by Ceres’ gravitational field on March 6. However, instead of the asteroid pulling the test mission directly into orbit, Dawn will float in front of Ceres before the asteroid’s gravitational field attracts the shuttle. Dawn is scheduled to enter its initial 8,400-mile-high orbit by April 23, as indicated by a blog entry signed by Marc Rayman, the mission’s executive engineer. On December 29, the space shuttle was around 400,000 miles away from the asteroid and moving closer at a 450 mph.
Compared to Vesta, Dawn’s first pit stop, Cares is significantly different. While Vesta is irregular in shape, full of impact craters and generally rocky, Ceres is surrounded by ice and may even have an underground sea with liquid water. Confirming these assessments about the asteroid depends on Dawn. The first close-up images of Ceres will be taken by the spacecraft within the next month.
Image Source: Universe Today